Dissecting the components controlling root‐to‐shoot arsenic translocation in Arabidopsis thaliana

Abstract

Summary • Arsenic (As) is an important environmental and food-chain toxin. We investigated the key components controlling As accumulation and tolerance in Arabidopsis thaliana. • We tested the effects of different combinations of gene knockout, including arsenate reductase (HAC1), γ-glutamyl-cysteine synthetase (γ-ECS), phytochelatin synthase (PCS1) and phosphate effluxer (PHO1), and the heterologous expression of the As-hyperaccumulator Pteris vittata arsenite efflux (PvACR3), on As tolerance, accumulation, translocation and speciation in A. thaliana. • Heterologous expression of PvACR3 markedly increased As tolerance and root-to-shoot As translocation in A. thaliana, with PvACR3 being localized to the plasma membrane. Combining PvACR3 expression with HAC1 mutation led to As hyperaccumulation in the shoots, whereas combining HAC1 and PHO1 mutation decreased As accumulation. Mutants of γ-ECS and PCS1 were hypersensitive to As and had higher root-to-shoot As translocation. Combining γ-ECS or PCS1 with HAC1 mutation did not alter As tolerance or accumulation beyond the levels observed in the single mutants. • PvACR3 and HAC1 have large effects on root-to-shoot As translocation. Arsenic hyperac cumulation can be engineered in A. thaliana by knocking out the HAC1 gene and expressing PvACR3. PvACR3 and HAC1 also affect As tolerance, but not to the extent of γ-ECS and PCS1.

Effects of short-term arsenic exposure in Arabidopsis thaliana: tolerance versus toxicity responses

“…In non-hyperaccumulating plants such as A. thaliana tolerance to As is achieved through restriction of absorption by the roots or through limitation of translocation to the shoot, avoiding the spread of the contamination (Catarecha et al 2007, Wang et al 2018).…”

Cross species multi-omics reveals cell wall sequestration and elevated global transcription as mechanisms of boron tolerance in plants

“…Plants for RNAseq, metabolomics, and ionomics experiments, were grown hydroponically in 1/5-strength Hoagland's solution (Liu et al, 2010;Wang et al, 2018)…”

Targeted expression of the arsenate reductase HAC1 identifies cell type specificity of arsenic metabolism and transport in plant roots

“…For As uptake, efflux, and speciation, A. thaliana lines were grown hydroponically with 1/5 strength Hoagland nutrient solution ( Wang et al , 2018 ). Thirty-day-old plants were exposed to 5 µM As(V) for 24 h, with four replicates for each line.…”

“…Phosphate was withheld from the nutrient solution to facilitate As(V) uptake. As(V) uptake and As(III) efflux were estimated by measuring the changes in As speciation in the nutrient solution, as described previously ( Wang et al , 2018 ). At the end of As(V) exposure, roots were desorbed of apoplastic As in an ice-cold solution containing 1 mM K 2 HPO 4 , 0.5 mM Ca(NO 3 ) 2 , and 5 mM MES (pH 5.5) for 10 min ( Liu et al , 2010 ).…”

“…The authors documented that despite As(III) contents comparable with those in roots of wild-type plants, As(III) export from hac1-1 plants was much reduced in comparison with the wild type. This suggests that HAC1 has a specific role in the reduction of As(V) to generate As(III) for efflux ( Chao et al , 2014 ; Wang et al , 2018 ). These discoveries in A. thaliana have also been extended to rice.…”